1. Field of the Invention
The present invention relates to an internal combustion engine having a variable engine cycle, and a controller thereof.
2. Description of the Related Art
A variable cycle internal combustion engine having a structure that allows a 2-cycle internal combustion engine to run also at four cycles or six cycles has been proposed in Japanese Patent Unexamined Publication No. Heisei 7-238840(1995).
The above-mentioned publication discloses the following features: 1) running at different engine cycles, and inlet and exhaust valves consisting of a solenoid valve; 2) both a camshaft for four cycles and a camshaft for six cycles so that a rocker arm is driven by either of the camshafts in accordance with a displacement of the center axis of a locker hinge; 3) running either at four cycles or at six cycles by selection of the camshaft revolving speed; and 4) running at two cycles by opening and closing inlet and exhaust ports and a scavenging air port for the two-cycle action instead of using the inlet and exhaust valves, meanwhile when running at four cycles, the inlet and exhaust ports are opened and closed by inlet and exhaust valves disposed at an upper part of the combustion chamber.
The above-described solenoid-driven inlet and exhaust valves of feature 1) have technical problems. The mechanisms of features 2) and 3) have complicated structures for changing actions and thus result in decreased reliability and increased costs. As for the mechanism of feature 4), since in the case of the four-cycle action the inlet and exhaust ports and the scavenging air port for the two-cycle action remain as they are, whether or not the four-cycle action proceeds normally is not known; the disclosure with respect to feature 4) is insufficient.
The above-mentioned Japanese publication describes some means for realizing a variable cycle engine, but does not specifically disclose how to select the cycles or a control method.